Improvements in dentin bonding systems have influenced modern restorative dentistry. The desire for minimal invasiveness has resulted in more-conservative cavity design, which basically relies on the effectiveness of current dentin bonding systems. Interaction of adhesives with enamel and dentin is based on two systems, commonly described as etch-and-rinse and self-etch. Priming and bonding agents can be separate or combined, resulting in two- or three-step systems for etch-and-rinse adhesives and one- or two-step systems for self-etch adhesives. Self-etch systems use acidic functional monomers that simultaneously demineralize and impregnate tooth structures. Etch-and-rinse and self-etch systems have advantages and disadvantages, which are primarily related to the simplified bonding procedures required under clinical conditions. Knowledge of the composition, characteristics, and mechanisms of adhesion for each adhesive system is critical in selecting the ideal adhesive materials for clinical use. (J Oral Sci 56, 1-9, 2014)

We used microcomputed tomography (micro-CT) to evaluate the effects of basic fibroblast growth factor (FGF-2) contained in absorbable collagen sponges on angiogenesis and bone regeneration in rat calvarial non-critical-size bone defects. Two symmetrical non-critical-size calvarial bone defects (diameter, 2.7 mm) were created in male Fisher rats. An absorbable collagen sponge with or without FGF-2 (0.1% or 0.3%) was implanted into each defect. Blood vessel volume and bone volume were calculated using software. On day 28, blood vessel volume and bone volume were significantly greater in the 0.3% and 0.1% FGF-2 groups than in the control group. FGF-2 concentration-dependently increased blood vessels and bone formation in non-critical-size bone defects in rat calvaria. (J Oral Sci 56, 17-22, 2014)

We evaluated the ability of platelet-derived growth factor (PDGF) to promote bone augmentation beyond the skeletal envelope in rat calvaria. The calvariae of 14 rats were exposed, and two plastic caps–one with 0.03% PDGF and a chitosan sponge and one with a chitosan sponge alone–were placed. Microcomputed tomography and histologic sections were used to determine the amount of bone augmentation within the plastic caps. Bone volume was calculated using measurement software. Bone volume and amount of bone augmentation were significantly greater in the PDGF group than in the control group. In conclusion, a chitosan sponge containing 0.03% PDGF enhanced bone formation beyond the skeletal envelope in rat calvaria. (J Oral Sci 56, 23-28, 2014)

The aim of this study was to evaluate the response of rat subcutaneous tissue to Portland cement combined with two different radiopacifying agents, iodoform (CHI3) and zirconium oxide (ZrO2). These materials were placed in polyethylene tubes and implanted into the dorsal connective tissue of Wistar rats for 7 and 15 days. The specimens were then stained with hematoxylin and eosin, and inflammatory reaction parameters were evaluated by light microscopy. The intensity of the inflammatory response to the sealants was analyzed by two blind calibrated observers throughout the experimental period. Histological analysis showed that all the materials caused a moderated inflammatory reaction at 7 days, which then diminished with time. At 15 days, the inflammatory reaction was almost absent, and fibroblasts and collagen fibers were observed indicating normal tissue healing. The degrees of the inflammatory reaction on different days throughout the experimental period were compared using the non-parametric Kruskal-Wallis test. Statistical analysis demonstrated no significant differences amongst the groups, and Portland cement associated with radiopacifying agents gave satisfactory results. Therefore, Portland cement used in combination with radiopacifying agents can be considered a biocompatible material. Although our results are very encouraging, further studies are needed in order to establish safe clinical indications for Portland cement combined with radiopacifying agents. (J Oral Sci 56, 29-34, 2014)

Chemomechanical procedures can be used to eliminate bacteria from root canals. However, detectable bacteria sometimes remain because of the complexity of the root canal system. Endodontic passive ultrasonic irrigation (PUI) with hydrogen peroxide (H2O2) may be a promising option for increasing bactericidal hydroxyl radical (HO•) generation. In this in vitro experiment, we examined the effects of HO• generated using PUI and a low concentration of H2O2. An ultrasonic tip was submerged in 0.45 mol/L (1.5%) H2O2 in a microfuge tube. H2O2 was activated by an ultrasonic unit, the tip of which was kept centered in the tube, to mimic PUI. HO• generation was detected by electron spin resonance spectroscopy. An Enterococcus faecalis suspension in H2O2 was then preparedand activated as described above. Bactericidal effects were assessed by viable counting. Two-way analysis of variance and Tukey’s test were used to assess the statistical significance of differences among groups (P < 0.05). HO• generation and bactericidal activity were significantly increased by PUI in H2O2 in a time-dependent manner and were significantly higher than with H2O2 alone or with PUI in a Tris-HCl suspension. These results suggest that PUI in the presence of a low H2O2 concentration is a promising new disinfection strategy. (J Oral Sci 56, 35-39, 2014)

In the cerebral cortex, fast-spiking (FS) cells are the principal GABAergic interneurons and potently suppress neural activity in targeting neurons. Some FS neurons make synaptic contacts with themselves. Such synapses are called autapses and contribute to self-inhibition of FS neural activity. β-Adrenoceptors have a crucial role in regulating GABAergic synaptic inputs from FS cells to pyramidal (Pyr) cells; however, the β-adrenergic functions on FS autapses are unknown. To determine how the β-adrenoceptor agonist isoproterenol modulates inhibitory synaptic transmission in the autapses of FS cells, paired whole-cell patch-clamp recordings were obtained from FS and Pyr cells in layer V of rat insular cortex. Previous studies found that isoproterenol (100 μM) had pleiotropic effects on unitary inhibitory postsynaptic currents (uIPSCs) in FS→Pyr connections, whereas autapses in FS cells were always facilitated by isoproterenol. Facilitation of autapses by isoproterenol was accompanied by decreases in the paired-pulse ratio of second to first uIPSC amplitudes and the coefficient of variation of the uIPSC amplitude, which suggests that β-adrenergic facilitation is likely mediated by presynaptic mechanisms. The discrepancy between isoproterenol-induced modulation of uIPSCs in FS autapses and in FS→Pyr connections may reflect the presence of different presynaptic mechanisms of GABA release in each synapse. (J Oral Sci 56, 41-47, 2014)

The α1-adrenoceptor agonist phenylephrine and the β-adrenoceptor agonist isoproterenol have opposite effects on evoked EPSPs (eEPSPs) in the cerebral cortex. The suppressive effects of phenylephrine on eEPSPs are mediated by modulation of postsynaptic glutamate receptors, whereas enhancement of eEPSPs by isoproterenol is due to facilitation of glutamate release from presynaptic terminals. The present study used whole-cell patch-clamp recordings from layer V pyramidal neurons in visuocortical slice preparations to assess the effects of phenylephrine and isoproterenol on the release probability of γ-aminobutyric acid (GABA). The present study recorded evoked inhibitory postsynaptic potentials (eIPSCs) by repetitive electrical stimulation (duration, 100 μs; 10 stimuli at 33 Hz) and miniature IPSCs (mIPSCs). The effects of phenylephrine (100 μM) depended on the amplitude of eIPSCs: phenylephrine decreased the paired-pulse ratios (PPRs) of eIPSCs with smaller amplitudes (<~600 pA) but increased PPRs of eIPSCs with larger amplitude. Phenylephrine also exhibited amplitude-dependent modulation of mIPSCs, i.e., an increase in the frequency of smaller mIPSC events (<~20 pA) and a decrease in the frequency of larger events. These findings suggest that α1-adrenoceptor activation facilitates GABA release from a subpopulation of GABAergic terminals that induce smaller-amplitude IPSCs in postsynaptic neurons. In contrast, isoproterenol (100 μM) consistently decreased the PPR of eIPSCs and increased the frequency of mIPSCs, suggesting that presynaptic β-adrenoceptors increase release probability from most GABAergic terminals. The complexity of adrenoceptor modulations in GABAergic synaptic transmission by α1-adrenoceptor and β-adrenoceptor activation may be due to the presence of pleiotropic subtypes of GABAergic interneurons in the cerebral cortex. (J Oral Sci 56, 49-57, 2014)

This study aimed to investigate a causal relationship between the stability of orthodontic anchor screws (screws) and the degree of their proximity to the root (root proximity) using mobility test device (Periotest) and cone-beam computed tomography (CBCT). In total, 165 (diameter 1.6 mm; length 8 mm) screws in 58 patients (average age, 24.4 ± 8.5 years) were evaluated. After screw placement, CBCT was used for diagnostic imaging of the area around the site. Root proximity was evaluated and categorized into three groups: A, no contact; B, single contact; and C, multi-contact. The Periotest value was used to assess screw stability. The screw failure rate according to root proximity significantly differed between categories A and C. In addition, failure rate significantly differed between mandibular screws with and without root contact. Periotest values in categories A and C were significantly higher in the mandible than in the maxilla. Mandibular screws had greater mobility than maxillar screws, even when the screw avoided root contact. The lower stability of mandibular screws with root contact might be related to their greater mobility. (J Oral Sci 56, 59-65, 2014)

Melatonin is produced by the pineal gland and regulates various physiological processes including osteoblast differentiation and bone formation. Bone sialoprotein (BSP) is a mineralized connective tissue-specific protein expressed in the early stage of cementum and bone mineralization. To elucidate the effects of melatonin on human BSP gene expression, we utilized human Saos2 osteoblast-like cells. Melatonin (100 nM) increased the level of BSP mRNA at 3 h, and the level became maximal at 12 and 24 h. We then investigated the melatonin-induced transcriptional activity of luciferase constructs (between -84LUC and -868LUC) including different lengths of the human BSP gene promoter transfected into Saos2 cells. The effects of melatonin abrogated in constructs included 2-bp mutations in the two cAMP response elements (CRE1 and CRE2). The effects of melatonin were suppressed by protein kinase A, tyrosine kinase, ERK1/2 and phosphatidylinositol 3-kinase inhibitors. Gel mobility shift assays showed that melatonin increased the binding of nuclear proteins to CRE1 and CRE2, and antibodies against CRE binding protein 1 (CREB1), phospho-CREB1, c-Fos, c-Jun, JunD and Fra2 disrupted CRE1 and CRE2 protein complex formation. These data indicate that melatonin induces BSP transcription via the CRE1 and CRE2 elements in the human BSP gene promoter. (J Oral Sci 56, 67-76, 2014)

Anaphylactic shock is characterized by increased capillary permeability and a decline in blood pressure due to excessive production of IgE. Midazolam (MDZ) is reported to have immunomodulatory properties. However, little is known about the effect of MDZ on the production of IgE antibody. We examined whether MDZ can suppress antigen-specific and total IgE production followed by IgE class switch recombination (CSR). MDZ was administered intraperitoneally to mice prior to ovalbumin (OVA) plus native cholera toxin (nCT) immunization. Serum OVA-specific and total IgE responses, and surface IgE-positive B cells were analyzed by ELISA and flow cytometry. Furthermore, expression levels of CSR-associated molecules such as germ-line transcript ε (εGLT), germ-circle tanscript ε (εCT), AID, and Id2 in the spleen were compared. The levels of interferon-gamma (IFN-γ) and interleukin (IL)-4 mRNA and protein were also examined in the spleen and serum. MDZ significantly suppressed OVA-specific and total IgE levels in plasma and surface IgE-positive B cells in the spleen. Moreover, MDZ-treated mice had significantly reduced levels of εGLT and εCT. Furthermore, although the levels of IFN-γ mRNA and protein were significantly elevated, those of IL-4 were reduced in MDZ-treated mice. Therefore, MDZ may be an important modulator of allergic responses through its ability to downregulate IgE production. (J Oral Sci 56, 77-83, 2014)

To establish a basic strategy for prevention of aspiration pneumonia in patients with motor and intellectual disabilities, we investigated oral opportunistic pathogen (OOP) infections in 31 such patients who were resident at a welfare home. Patients received special oral care from a dental hygienist once a week. OOP samples were collected by scraping the dorsal surface of the tongue, and then cultured. For each patient, the basic reasons for admission and the degree of intellectual disability and mobility were recorded. OOPs were found in 61.3% of the patients, of which methicillin-sensitive Staphylococcus aureus (MSSA) was the most commonly detected (38.7%). A significantly high proportion of male patients were OOP-positive, and a significantly high proportion of patients with mental retardation were Candida sp.-positive. However, multivariate logistic regression revealed that disability was not associated with OOP positivity. No correlation was found between OOP positivity and disability. Nevertheless, special oral care may be beneficial for maintenance of oral health in patients with disabilities. (J Oral Sci 56, 85-89, 2014)

Snus (Swedish moist snuff) causes lesions in the oral mucosa at the location where pinches are regularly placed. In addition, some patients develop irreversible local gingival recession and sometimes ulcers with perforations to the roots. Such injuries lead to denuded roots that are at risk for caries and periodontal disease, with subsequent esthetic consequences. Therapy for irreversible local gingival recession is currently lacking. In the present report, we describe two cases of successful surgical treatment for irreversible lesions caused by snus. (J Oral Sci 56, 91-94, 2014)

Calcifying epithelial odontogenic tumor is a benign neoplasm, but its local destructive potential may lead to the formation of major bone defects. Microscopically, there are some histological variants. Among them, we highlight the clear cell variant due to its more aggressive behavior and a higher incidence of relapse. In this context, it is pertinent to describe the clear cell variant of calcifying epithelial odontogenic tumor. Despite the large bone defect formed in the posterior region of the mandible, conservative treatment associated with guided bone regeneration assured complete bone formation and the absence of recurrence in an 8-year follow-up period. (J Oral Sci 56, 95-98, 2014)